1. Field of the Invention
The present invention relates to an image recording method and apparatus and a recording sheet for use therewith, in which an image is recorded or displayed in colors, employing an electrochromic material that has light absorption reversibly changing in the electrochemical oxidation/reduction reaction.
2. Description of the Related Art
One of the display elements is an electrochromic (EC) element in which light absorption is reversibly changed through the electrochemical oxidation/reduction reaction. The EC element has a structure in which an EC material thin film and an electrolytic solution or solid electrolyte are laminated between the transparent electrodes, or a structure in which an EC material is dissolved in electrolytic solution.
In this EC element, by applying a voltage via a transparent electrode to the EC material thin film and the solid electrolyte laminated, electrochemical oxidation/reduction reaction is caused to bring about the coloring or decoloring reaction reversibly on the entire face of the EC material thin film. The EC element has a low driving voltage, and a memory property, and is the light absorption type to make a clear display without dependency on the angle of visibility under strong external lights.
Conventionally, the image recording apparatus using the EC element of this kind involved a driving method with a simple matrix in which a plurality of X electrodes with the EC material carried and a Y electrode are arranged in parallel at high definition, and the display pixels are made at their intersections.
However, the above image recording apparatus using the EC material was involved in bringing about the coloring or decoloring reaction at arbitrary part in such a way that a voltage is applied to the XY electrodes oppositely arranged in a matrix form, and the display pixels are made at their intersections, whereby a great number of wirings are required. Also, the composition of EC material became complex to increase the manufacturing costs.
The present invention has been achieved in the light of the above-mentioned situation, and it is an object of the invention to provide an image recording method and apparatus and a recording sheet for use therewith in which an image of free pattern can be recorded and displayed without forming the complex wirings in the EC material, and to reduce the manufacturing costs of the image recording apparatus using the EC material.
In order to accomplish the above object, according to a first aspect of the present invention, there is provided an image recording method employing a recording sheet having a coloring layer made of an electrochromic material and an electrolytic layer with an increasing electrical conductivity in a specific temperature range, characterized by including moving a recording head with a plurality of heating elements arranged in a linear direction relative to the surface of the recording sheet in the direction orthogonal to the linear direction while at the same time applying a voltage to the front and back faces of the recording sheet, and causing a coloring reaction only in a part where heat is applied by the heating elements to form an image on the recording sheet.
With this image recording method, the recording head is moved relative to the recording sheet, and a thermal stimulus is given from the heating elements to a desired display pixel, while at the same time a voltage is applied to the front and back faces of the recording sheet, whereby only a part where heat is applied by any heating elements is subjected to coloring reaction to form an image on the recording sheet. That is, a part where voltage and heat are applied becomes display pixels. Accordingly, an image of free pattern can be recorded and displayed without forming the complex wirings like a matrix in the EC material.
Also, according to a second aspect of the invention, there is provided an image recording method employing a recording sheet having a coloring layer made of an electrochromic material, characterized by including moving a recording head with a plurality of independent driving electrodes arranged in a linear direction relative to the surface of the recording sheet in the direction orthogonal to the linear direction, and causing a coloring reaction only in a part where voltage is applied by the independent driving electrodes to form an image on the recording sheet.
With this image recording method, the recording head having a plurality of independent driving electrodes arranged is moved relative to the surface of the recording sheet, and a part where voltage is applied by any independent driving electrodes is subjected to the coloring reaction to form an image on the recording sheet. That is, a part where voltage is applied becomes display pixels. Accordingly, an image of free pattern can be recorded and displayed without forming the complex wirings like a matrix in the EC material.
Further, according to a third aspect of the invention, there is provided the image recording method, characterized in that the recording sheet is a laminated recording sheet in which a plurality of recording sheets coloring in different colors are laminated in multiple stages, in which an image is formed by applying selectively a voltage to a recording sheet of each color.
With this image recording method, a multi-color image can be recorded and displayed by applying a voltage selectively to the recording sheet for each color of yellow (Y), magenta (M) and cyan (C), for example.
According to a fourth aspect of the invention, there is provided the image recording method, characterized in that the recording sheet is a multi-color recording sheet having a plurality of coloring cells dispersed within a coloring layer, the plurality of coloring cells coloring in different colors in accordance with an applied voltage, and a plurality of electrolyte cells dispersed within an electrolytic layer corresponding to the coloring species of the coloring cells, each of the electrolyte cells having an increasing electrical conductivity in a different temperature range, wherein an image is formed by heating selectively the electrolyte cells in a predetermined temperature range in accordance with the coloring species, while applying a predetermined voltage to the multi-color recording sheet in accordance with the coloring species.
With this image recording method, the coloring material for each color of yellow (Y), magenta (M) and cyan (C) is heated in a predetermined temperature range in accordance with the coloring species at an applied voltage in accordance with the coloring species, and selectively colored, whereby a multi-color image can be recorded and displayed with a single layer structure of the coloring layer.
Further, according to a fifth aspect of the invention, there is provided an image recording apparatus comprising a fixed planar electrode for laying thereon a recording sheet having a coloring layer made of an electrochromic material and an electrolytic layer with an increasing electrical conductivity in a specific temperature range, a recording head having a strip movable electrode in contact with an upper face of the recording sheet, a sliding electrode for sliding with the fixed planar electrode, and a plurality of heating elements for applying heat via the strip movable electrode to the recording sheet, the plurality of heating elements being arranged linearly, the recording head heating selectively the heating elements while applying a voltage between the strip movable electrode and the sliding electrode, and movement means for moving the recording head relative to the planar support along the direction orthogonal to a direction where the heating elements are arranged.
With this image recording apparatus, the recording head is moved by the movement means, and a thermal stimulus is given to the recording sheet by any heating elements at any movement position while at the same time a voltage is applied via the fixed planar electrode and the strip movable electrode to the recording sheet, whereby only a part where heat is applied is subjected to the coloring reaction to form an image on the recording sheet. That is, a part where voltage and heat are applied becomes display pixels. Accordingly, an image of free pattern can be recorded and displayed without forming the complex wirings like a matrix in the EC material.
Further, according to a sixth aspect of the invention, there is provided an image recording apparatus comprising a fixed planar electrode for laying thereon a recording sheet having a coloring layer made of an electrochromic material, a recording head having a plurality of independent driving electrodes arranged linearly, and a sliding electrode for sliding with the fixed planar electrode, the recording head selectively applying a voltage between the independent driving electrodes and the sliding electrode, and movement means for moving the recording head relative to the planar support along the direction orthogonal to a direction where the independent driving electrodes are arranged.
With this image recording apparatus, the recording head is moved by the movement means, and any independent driving electrodes provided on the recording head are selectively driven to bring about the coloring reaction only in a part where voltage is applied to form an image on the recording sheet. That is, a part where voltage is applied becomes display pixels. Accordingly, an image of free pattern can be recorded and displayed without forming the complex wirings like a matrix in the EC material.
Also, according to a seventh aspect of the invention, there is provided the image recording apparatus, characterized in that the fixed planar electrode is formed to be larger than the recording sheet, and the sliding electrode is disposed in the recording head to slide with an exposed portion of the fixed planar electrode extending out of the recording sheet.
With this image recording apparatus, the sliding electrode of the recording head slides with the portion of the fixed planar electrode extending out of the recording sheet, whereby the voltage can be applied to the EC material at each movement position of the recording head with a simple structure.
Also, according to an eighth aspect of the invention, there is provided the image recording apparatus, characterized in that the recording head has the sliding electrode disposed at an end portion in the direction where the heating elements or the independent driving electrodes are arranged.
With this image recording apparatus, the sliding electrode is disposed at the end portion of the recording head in the longitudinal direction, whereby the structure of the recording head can be simplified.
Also, according to a ninth aspect of the invention, there is provided the image recording apparatus, characterized in that a multi-layer recording sheet consists of a plurality of recording sheets coloring in different colors that are laminated in multiple stages and transparent electrodes interposed between the recording sheets to be exposed at the sheet end portion, and a plurality of sliding electrode are provided on the side of the recording head to slide with the transparent electrodes interposed.
With this image recording apparatus, a voltage is selectively applied from the plurality of sliding electrodes provided on the recording head to the transparent electrodes and the fixed planar electrode provided in the recording sheet, whereby an image of free pattern can be recorded and displayed on the recording sheet coloring in different colors.
Also, according to a tenth aspect of the invention, there is provided the image recording method, characterized in that the recording sheet is a multi-color recording sheet having a plurality of coloring cells dispersed within a coloring layer, the plurality of coloring cells coloring in different colors in accordance with an applied voltage, and a plurality of electrolyte cells dispersed within an electrolytic layer corresponding to the coloring species of the coloring cells, each of the electrolyte cells having an increasing electrical conductivity in a different temperature range.
With this image recording apparatus, a combination of different voltage and different heat is applied to the coloring cell provided for each color, thereby making it possible to control the coloring, whereby an image of free pattern can be recorded and displayed in multiple colors.
According to an eleventh aspect of the invention, there is provided a recording sheet characterized by having a coloring layer made of an electrochromic material, and comprising an electrolytic layer provided in contact with the coloring layer and made of an electrolyte with an increasing electrical conductivity in a specific temperature range.
With this multi-color recording sheet, the recording sheet is selectively heated in a state where voltage is applied to the recording sheet, so that only the heated part is colored. Thereby, a desired image can be recorded and displayed on the multi-color recording sheet.
Also, according to a twelfth aspect of the invention, a multi-color recording sheet characterized in that a plurality of recording sheets made of an electrochromic material and coloring in different colors are laminated in multiple stages, and the transparent electrodes are interposed between the recording sheets to be exposed at the end portion of layer.
With this multi-color recording sheet, a multi-color image can be recorded and displayed by coloring the recording sheets in different colors.
Also, according to a thirteenth aspect of the invention, there is provided the multi-color recording sheet, characterized in that a plurality of recording sheets coloring in different colors are laminated in multiple stages, and the transparent electrodes are interposed between the recording sheets to be exposed at the sheet end portion.
With this multi-color recording sheet, each recording sheet is selectively heated while voltage is applied to the recording sheet, so that color comes out only in the heated part of the recording sheet where voltage is applied. Thereby, a multi-color image can be recorded and displayed on the multi-color recording sheet.
Also, according to a fourteenth aspect of the invention, there is provided the multi-color recording sheet, characterized in that the coloring layer has a plurality of coloring cells coloring in different colors in accordance with an applied voltage dispersed therein, and the electrolytic layer has a plurality of electrolyte cells with an increasing electrical conductivity in a different temperature range dispersed corresponding to the coloring species of the coloring cells.
With this multi-color recording sheet, an electrolyte cell corresponding to a desired coloring cell is set in a temperature range where electrical conductivity increases, while voltage is applied in accordance with the desired coloring species to the recording sheets, whereby the coloring cell corresponding to this electrolyte cell colors. Thereby, the coloring cell for specific color can be selectively colored, so that a multi-color image can be recorded and displayed in a single layer structure of the coloring layer.